This non-provisional application claims priority under 35 U.S.C. xc2xa7119(a) on Patent Application No. 2001-82902 filed in Japan on Mar. 22, 2001, which is herein incorporated by reference.
1. Field of the Invention
This invention relates to a vehicle body structure for increasing the stiffness of a vehicle body against side impact of a motor vehicle.
2. Description of the Related Art
In a motor vehicle, the structure of the side of a vehicle body, especially the structure of a floor portion, is important to provide a vehicle body effective for side impact. There is known an example of a conventional structure of the front side of a floor portion in a motor vehicle (i.e. sedan type passenger car) as shown in FIG. 8.
A brief description will now be given of the conventional structure with reference to FIG. 8.
A side sill (12) is disposed in a side edge portion of a front floor (11), and a center pillar (13) is provided upward the side sill (12).
Further, front of front floor cross member (15) and rear of front floor cross member (16) are provided in the neighborhood of a seat position between the side sill (12) above the front floor (11) and a floor tunnel (14) in the middle of the front floor (11). It should be noted that reference numeral 17 in FIG. 8 denotes a seat mounting bracket.
When such a vehicle is collided from the side, impact force toward inside of a vehicle compartment is applied to the center pillar (13) and around the lower portion of front and rear door (not shown) in many cases. Not only when such impact is applied to the center pillar (13), but also when it is applied to the front or rear door, the impact force is transmitted to the center pillar (13) and therefore, the center pillar (13) (especially, its lower portion) has an inclination to be deformed toward the inside of the vehicle compartment.
Therefore, to avoid the penetration of the center pillar (13) into the vehicle compartment in vehicular side collision, it is important to ensure the sufficient stiffness of the front floor (11) supporting the basic portion of the center pillar (13). Cross members (15), (16) are most important to increase the stiffness of the front floor (11).
These cross members (15), (16), as shown in FIG. 9, have substantially hat-shaped cross-sections, and it is very effective to make larger shape of cross-sections of these cross members (15), (16), especially the heights (H1), (H2) thereof in order to increase the stiffness of the front floor (11).
However, since a front seat will be provided above these cross members (15), (16), it is difficult to make larger the heights (H1), (H2) thereof. Especially, as the rear of the front floor cross member (16) is positioned in the neighborhood of the foots of a passenger sitting on a rear seat, the height (H2) of the cross member (16) is required to be low.
Therefore, if the sufficient body stiffness against side impact cannot be achieved only by reinforce of the cross members (15), (16), it is necessary to considerably reinforce the center pillar (13), the side sill (12), a front pillar (not shown), and so forth.
Japanese Utility Model No. 2567290 discloses the technology of rising the stiffness of the vehicle body against side impact that allots impact in side collision to a first cross member (corresponding to the front of the front floor cross member (15)) provided in front of a third cross member and a second cross member provided at the rear of the third cross member, and transmits the impact to the floor tunnel by opposing the third cross member (corresponding to the rear of the front floor cross member (16)) to the floor tunnel at a predetermined intervals. However, in this case, a problem similar to the above-described one is encountered, since the pillar, the side sill and so on are heavily burdened, and thus they need to be considerably reinforced.
It is therefore an object of the present invention to provide a body structure, which enables an improvement in stiffness of a vehicle body against side impact efficiently by a simple reinforcing structure.
To attain the above object, according to the present invention, a first cross member, a second cross member, and a third cross member are provided on a floor portion positioned between a side sill portion provided in both side portions of a vehicle body and a floor tunnel portion provided in a longitudinal direction in the middle of the vehicle body.
One end of the first cross member is supported on the side sill portion, and the other end of the first cross member is provided on the floor tunnel portion to support the front of a seat, and one end of the second cross member is provided on the side sill portion and the other end of the second cross member is provided on the floor tunnel portion to support the rear of the seat. The third cross member is also disposed between the first cross member and the second cross member to be parallel with them such that one end of thereof is provided on the side sill portion, the front end of thereof is provided on the first cross member, and the rear end of thereof is provided on the second cross member.
Therefore, since side impact of the vehicle body is also applied to the third cross member in addition to the first cross member and the second cross member in side collision, it becomes easy to prevent the penetration of a vehicle side portion into the vehicle compartment in side impact